Just thought I would let you know that I understand exactly how you feel. When my first DGD was born, my H and I were both so happy, glad to do anything we could to help. We are older grandparents (in our 70's) but we still looked after GD for a full day a week at first to give DIL a break and then two days when she wanted to return to work. She said she appreciated this and we said all we ask is that we be included in Christmas concerts, sports days etc. where GPs can attend. When GD started pre-school we waited for an invitation. It didn't come so I asked when the Nativity play was and her reply was "Oh, they are not having one this year" which I thought was odd but thought no more about it. My S knew nothing of this and called in a few days later and as he was leaving he showed me some photos on his phone of, you have guessed it, the Nativity with my gorgeous little gd as an angel. I cried. All I can say is I think you will have to do what I have done and steel yourself against these disappointments, it is just so hurtful and I think in my case the lie was the worse part. It probably has nothing to do with your S, it will most likely be his wife. I do send you good wishes and hope next year will be different for you.